/******************************************************************************
 * Spine Runtimes License Agreement
 * Last updated January 1, 2020. Replaces all prior versions.
 *
 * Copyright (c) 2013-2020, Esoteric Software LLC
 *
 * Integration of the Spine Runtimes into software or otherwise creating
 * derivative works of the Spine Runtimes is permitted under the terms and
 * conditions of Section 2 of the Spine Editor License Agreement:
 * http://esotericsoftware.com/spine-editor-license
 *
 * Otherwise, it is permitted to integrate the Spine Runtimes into software
 * or otherwise create derivative works of the Spine Runtimes (collectively,
 * "Products"), provided that each user of the Products must obtain their own
 * Spine Editor license and redistribution of the Products in any form must
 * include this license and copyright notice.
 *
 * THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
 * BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *****************************************************************************/

using System;
using System.Collections.Generic;

namespace Spine
{

    /// <summary>Stores mix (crossfade) durations to be applied when AnimationState animations are changed.</summary>
    public class AnimationStateData
    {
        internal SkeletonData skeletonData;
        readonly Dictionary<AnimationPair, float> animationToMixTime = new Dictionary<AnimationPair, float>(AnimationPairComparer.Instance);
        internal float defaultMix;

        /// <summary>The SkeletonData to look up animations when they are specified by name.</summary>
        public SkeletonData SkeletonData { get { return skeletonData; } }

        /// <summary>
        /// The mix duration to use when no mix duration has been specifically defined between two animations.</summary>
        public float DefaultMix { get { return defaultMix; } set { defaultMix = value; } }

        public AnimationStateData(SkeletonData skeletonData)
        {
            if (skeletonData == null) throw new ArgumentException("skeletonData cannot be null.", "skeletonData");
            this.skeletonData = skeletonData;
        }

        /// <summary>Sets a mix duration by animation names.</summary>
        public void SetMix(string fromName, string toName, float duration)
        {
            Animation from = skeletonData.FindAnimation(fromName);
            if (from == null) throw new ArgumentException("Animation not found: " + fromName, "fromName");
            Animation to = skeletonData.FindAnimation(toName);
            if (to == null) throw new ArgumentException("Animation not found: " + toName, "toName");
            SetMix(from, to, duration);
        }

        /// <summary>Sets a mix duration when changing from the specified animation to the other.
        /// See TrackEntry.MixDuration.</summary>
        public void SetMix(Animation from, Animation to, float duration)
        {
            if (from == null) throw new ArgumentNullException("from", "from cannot be null.");
            if (to == null) throw new ArgumentNullException("to", "to cannot be null.");
            AnimationPair key = new AnimationPair(from, to);
            animationToMixTime.Remove(key);
            animationToMixTime.Add(key, duration);
        }

        /// <summary>
        /// The mix duration to use when changing from the specified animation to the other,
        /// or the DefaultMix if no mix duration has been set.
        /// </summary>
        public float GetMix(Animation from, Animation to)
        {
            if (from == null) throw new ArgumentNullException("from", "from cannot be null.");
            if (to == null) throw new ArgumentNullException("to", "to cannot be null.");
            AnimationPair key = new AnimationPair(from, to);
            float duration;
            if (animationToMixTime.TryGetValue(key, out duration)) return duration;
            return defaultMix;
        }

        public struct AnimationPair
        {
            public readonly Animation a1;
            public readonly Animation a2;

            public AnimationPair(Animation a1, Animation a2)
            {
                this.a1 = a1;
                this.a2 = a2;
            }

            public override string ToString()
            {
                return a1.name + "->" + a2.name;
            }
        }

        // Avoids boxing in the dictionary.
        public class AnimationPairComparer : IEqualityComparer<AnimationPair>
        {
            public static readonly AnimationPairComparer Instance = new AnimationPairComparer();

            bool IEqualityComparer<AnimationPair>.Equals(AnimationPair x, AnimationPair y)
            {
                return ReferenceEquals(x.a1, y.a1) && ReferenceEquals(x.a2, y.a2);
            }

            int IEqualityComparer<AnimationPair>.GetHashCode(AnimationPair obj)
            {
                // from Tuple.CombineHashCodes // return (((h1 << 5) + h1) ^ h2);
                int h1 = obj.a1.GetHashCode();
                return (((h1 << 5) + h1) ^ obj.a2.GetHashCode());
            }
        }
    }
}
